Known all-in-one diapers include an impervious outer layer and mounted into this an absorbing material, wherein the outer layer is so arranged and shaped that it can be made to fit tightly to the body of the user and restrict the area inside from the environment. The absorbing material may be based on cellulose or be made of synthetic material.
The construction of such diapers can vary within wide limits. One intention has been to arrange the absorbing material in such a way at the impervious layer that humidity absorbed as far as possible is prevented from reaching the skin of the user beyond the place of entry and for that purpose a number of different types of pervious inner protecting layers with or without perforated or otherwise open portions. The absorbing material will then to a major part be enclosed between an outer impervious and one inner pervious layer which later has as main purpose to stabilize the absorbing material. The diaper as a whole will then after being put on form a trouser like article where a central portion by stretching or wrinkling strings attached to the material is adapted to contract so that a good fit at the crotch of the user is achieved.
With known diapers, it is so that both urine and feces especially the later will remain against the skin of the user which naturally is unwanted as, among other things, irritation of the skin easily occur. Concerning urine, it is found that even if it is absorbed by the absorbent material, the damp surface thereof will contract the skin which is undesirable.
With the majority of all diapers, the absorbing material is arranged in such a way that it in use contacts or is close to the skin of the user. This means that urine and feces will be spread or distributed in the space between the skin and absorbing layer. On urinating, it often occurs with larger volumes that urine will come outside the absorbing material and seep out at the edges of the outer layer of diaper and wet the clothing. On manufacturing of diapers and estimating of necessary volume of absorbing material, it is counted from a theoretical average volume and the ability and speed of absorption will be adapted thereto. When the volume exceeds the calculated volume, leakage is unavoidable. Generally it may be said that one disadvantage with absorption material used today is that it lacks the ability to quickly absorb anything but rather small amounts despite having a total capacity of absorption which is usually sufficient.
In known diapers, the urine will hit a generally flat surface of the absorption body which is unable to immediately absorb more than a restricted volume. Thus, the urine volume will spread over the surface of the absorption body or adjacent skin portions or impervious or surface layers, respectively, resulting in an undesired leakage.
Because of their shape and location, known absorption bodies can be easily pressed together and deformed which leads to reduced absorption ability in such portions which are compressed and also possibly leakage.
The circumstance that fluid will be absorbed over the surface only of known absorption bodies means that their absorption ability not is taken full advantage of.
Long before the modern diapers came into use there were several types of trouser like articles inside which could be placed cellulose wadding or similar absorbing material. In order to restrict the spreading of urine and feces as much as possible and position the absorbing material, U.S. Pat. No. 2,538,758 suggests such a trouser like article with buttoning at one side and provided with a partly double crotch portion where an inner layer to the major part was removed so that a pocket with excess from the upper side for a cushion like body of absorbing material was formed. Stretching tape at each side of the inwardly open pocket were intended to secure tight fitting against legs and the skin outside the crotch portion. The intention behind the known construction was that urine and feces would end up directly in the absorbing material and not soil the inside of the remaining portion of the article.
In other respects, the known device had the same disadvantages with irritating skin etc. as other diapers where urine and feces are in contact with the skin.
U.S. Pat. No. 4,662,877 discloses an example of a later embodiment of the diaper device just mentioned and is of a disposable type. In an inner layer facing the user, there is an elongated opening allowing urine and feces to directly end up at the absorbing material which is directly accessible through said opening. As in the earlier example, the surface of the absorption body will directly contact the skin of the user having the result that urine will be spread over the skin before it is absorbed and that feces remains at the skin.
One feature with all diapers, both those of today and older ones is the following. However careful and however well fitted in a diaper is, i.e. snugly contacting around the legs and the body and at the crotch, the diaper will change its shape and be displaced as soon as any mentionable amount of urine is absorbed by the absorbing material. The increase of weight caused by the urine on the absorption body outwardly restricted by the outer layer of the diaper together with the change of structure caused by the absorption of liquid as well as the stiffness of this material result in a deformation of the total diaper and also prevent the tight fitting at the user. The result of this is naturally that leakage can occur both at next urinating occasion and when the user moves and/or sits down and compresses the displaced portions of the absorption body.